The present invention provides for methods for forming a low-k dielectric film on semiconductors or integrated circuits using a substituted organosilane compound as a low-k dielectric precursor.
The increase in semiconductor design integration by feature size reduction has resulted in increased levels of interconnect and increased utilization of dielectric low-k thin films. The dielectric film is used as insulation around metal lines of a device and contributes to the RC time constant that controls the device speed. As the semiconductor industry has striven to reduce resistance (R) by the use of copper metallization, the push to the use of low-k dielectrics is to reduce capacitance (C). Reducing capacitance by lowering the dielectric constant k to the inter and intra level dielectric (ILD) film can improve device performance by reducing the RC time delay, decreasing the cross talk between adjacent metal lines and lowering the power dissipation.
Traditionally, the material of choice for the ILD is silicon dioxide (SiO2) which can be prepared using silane, disilane or siloxane precursors in an oxidizing environment. The most popular deposition techniques for depositing ILD are chemical vapor deposition (CVD), low temperature plasma-enhanced CVD (PECVD), or high density plasma CVD (HDPCVD). However, the dielectric constant of the deposited SiO2 is relatively high at 4.0.
As the semiconductor industry moves to smaller width metal lines, low-k materials must have smaller dielectric constants. Industry publications have indicated that low-k materials with k values from 2.7 to 3.5 would be needed for 150 and 130 nm technology modes. When the industry moves to 100 nm technology and dimensions below that in the future, extra low-k (ELK) materials having a k value from 2.2 to 2.6 and ultra low-k (ULK) materials with a k value less than 2.2 will be necessary.
The semiconductor industry has developed several low-k materials to replace silicon dioxide that are inorganic, organic or hybrid materials. These materials can be deposited by either chemical vapor deposition (CVD) or spin-on deposition (SOD) methods. The CVD technique utilizes existing vacuum tools for depositing SiO2 that include lower temperature plasma enhanced CVD (PECVD) and high density plasma CVD (HDP-CVD). The SOD method uses spin coaters that have shown better extendibility to ELK or ULK by introducing pores in nanometer sizes. Newer materials such as fluorosilicate glass (FSG), carbon or carbon fluorine based films and carbon-doped SiO2 utilize CVD techniques. Materials such as polyimide, hydrogen silses quioxane (HSQ) and polyarylene ethers can be deposited using SOD techniques.
As such, a number of technologies to provide lower dielectric constant CVD materials have been demonstrated in the 3.5 to 2.6 range. However, there are far fewer alternatives for k values at or below 2.5 for CVD materials in ELK/ULK applications. The present invention provides for new materials for use as extra low dielectric CVD precursors in extra low-k CVD materials for the semiconductor industry.
Given the desires of the semiconductor industry for lower k value materials, new low-k CVD materials are being sought. The present invention provides a novel class of compounds useful for forming a film on a semiconductor or integrated circuit by acting as a precursor for the film formed when the compound is applied.
Substituted organosilane compounds other than methylsilane are used as precursors for forming a low-k dielectric film on the surfaces of semiconductors and integrated circuits. The resultant dielectric film formed will be an organosilicon polymer film on the surface of the device which will have low-k dielectric properties.
The substituted organosilane compounds are those having the formula R1SiR2R3R4 where R1 is a cyclic or acyclic hydrocarbon group other than H or methyl, and R2, R3 and R4 are the same or different and are selected from the groups consisting of H, CH3, vinyl or other hydrocarbon containing two or more carbon atoms, or R5R6R7SiRxe2x80x2SiR8R9R10 where R5, R6, R7, R8, R9, R10, are a cyclic or acyclic hydrocarbon group including H, and they can be the same or different; Rxe2x80x2 is a linking group between the two silicon atoms, and it can be a cyclic or acyclic hydrocarbon group, or (xe2x80x94R11xe2x80x94)SiR12R13 where R11 is a chelate hydrocarbon group containing two or more carbon atoms, R12 and R13 are a cyclic or acyclic hydrocarbon group including H, and they can be the same or different. The general structures for R1SiR2R3R4, or R5R6R7SiRxe2x80x2SiR8R9, R10, or (xe2x80x94R11xe2x80x94)SiR12R13 are illustrated below. 
These substituted organosilane compounds are precursors to the film formed and will react with the surface of the semiconductor or integrated circuit to form the low-k dielectric film having a dielectric constant below 2.5.